Paclitaxel is a well-known and approved (FDA AND HPB) chemotherapeutic drug for treatment of metastatic cancer. It is a natural product, isolated from a number of Taxus species.
However, the concentration of Paclitaxel in its natural resources is very low, in the order of 0.004 to 0.01% (w/w). Also, several structurally similar compounds occur along with Paclitaxel in Taxus species. This makes extraction and purification of the compound almost impractical in commercial scale.
Semisyntheses of paclitaxel from 10-DAB address the problem of its availability. However, purification of the synthetic compound to pharmaceutical grade remains challenging due to formation of a number of degradation products during synthesis. Similar problems are encountered in purification of Docetaxel, a synthetic analog of Paclitaxel.
Classical low pressure column chromatography for the purification of Paclitaxel and Docetaxel involves use of silica gel or alumina which are strong absorbent and may adversely participate in the separation process resulting in low selectivity and recovery. Also, handling and destruction of silica or alumina contaminated with toxic material is problematic.
Reverse phase chromatography on bonded silica gel column can be conducted only on a small laboratory scale. Furthermore, the process is labor and capital intensive.